# README – Elevation and Flood-Prone Areas Dataset – Rio Branco, Acre, Brazil

## Dataset Description
This dataset was created for the application of the Relative Elevation Model (REM) to classify flood-prone areas within the urban perimeter of Rio Branco, Acre, Brazil. The results were analyzed and described in a scientific article to be submitted to the Revista Brasileira de Geomorfologia.

## Dataset Structure
The dataset is organized in the following files and folders:

- QGIS Project (qgz): 
  - FloodRisk – Project file containing all layers and symbologies
- Readme.txt: This file with information about the data and methodology
- Vectors (shapefiles):
  - Acre_River – section of the Acre River
  - Brazil – country boundary
  - Brazilian_States – Brazilian states
  - chain_Acre_River – sampling line along the Acre River
  - South_American_countries – South American countries
  - UrbanPerimeter_of_RioBranco_AC_Brazil – urban perimeter of Rio Branco
- Rasters (.tif):
  - chain_IDW – IDW interpolation of elevation points
  - DEM_Extracted – DEM clipped to the urban perimeter
  - Digital_Elevation_Model_DEM – original DEM at 1 m resolution
  - Relative_Elevation_Model_REM – Relative Elevation Model (final result)
  - DEM_Flood_Risk_Classification.tif – DEM adjusted with symbology for **flood risk classification**
- Flood Classification and Flood History Table:
  - Flood_Risk_Classification_Table.xlsx – Excel file (.xlsx) containing two main tables:
    - Table 1 – Flood Susceptibility Classification Based on the REM: presents the classification of areas according to relative elevation, describing the susceptibility ranges and corresponding risk interpretations;
    - Table 2 – Historical Maximum Levels of the Acre River (1971–2024): lists the highest recorded levels of the Acre River in Rio Branco, including the river’s maximum height (in meters) and the date of occurrence.


## Data Sources
1. Digital Elevation Model (DEM)
   - Resolution: 1 meter
   - Source: WebGIS of RBGEO, Prefeitura de Rio Branco – AC, Brazil
   - All copyrights belong to Prefeitura de Rio Branco
2. Additional polygons (Brazil, Brazilian States, South American Countries)
   - Obtained from the **IBGE GeoSciences Portal**
3. Urban Perimeter of Rio Branco
   - Generated from the coordinates of the municipality's Master Plan descriptive memorial
4.Table 2 Data
   - DData obtained and organized based on: SERVIÇO GEOLÓGICO DO BRASIL. Sistema de Alerta de Eventos Críticos (SACE) – Bacia do Rio Acre. Brasília, DF: SGB, [n.d.]. Available at: https://www.sgb.gov.br/sace/acre_historico.php . Accessed on: September 26, 2025.
5. Other Data
   - Generated manually or processed using automatic tools in QGIS software

## REM Generation Methodology
1. Added the DEM vector file in QGIS
2. Generated the urban perimeter polygon based on the descriptive memorial of the Master Plan
3. Clipped the DEM to the urban perimeter area
4. Delimited the Acre River section within the urban perimeter
5. Extracted points and elevation values according to the DEM
6. Generated IDW of elevation points
7. Calculated REM using the field calculator: DEM – IDW = REM
8. Adjusted the DEM to **represent the flood risk classification**, generating the raster `DEM_Flood_Risk_Classification.tif`

## Analysis and Application
- Analysis performed by Lucas de Alencar Prado (<lucas.prado@sou.ufac.br>) and Waldemir Lima dos Santos
- Software used: QGIS version 3.40
- For the article study, data were adjusted according to the **flood risk classification table** available in `Flood_Risk_Classification_Table.csv`, enabling the **zoning of flood risk areas** within the urban perimeter of Rio Branco

## Spatial Reference System
- SIRGAS 2000 / UTM Zone 19S
- Unit: meters

## Important Notes
- Intended for scientific use and geospatial analysis only
- Users should cite the original DEM, urban perimeter, and IBGE polygons
- Respect copyrights of Prefeitura de Rio Branco and the standards of Revista Brasileira de Geomorfologia

## Contact
For questions or more information about the dataset, contact the study authors
